Monday, August 3, 2009

Ecotect within Revit

Isn't this useful, Ecotect solar analysis tools built into Revit. An early release of the Solar Radiation Technology plug-in for Revit will allow users to give feedback during the development of this feature. I've add my personal thoughts at the end of this post, the rest of you should head over to the Autodesk Labs site and start testing out the plug-in for yourselves.

Unwanted Solar gain is a major contributor towards unnecessary building energy consumption, particularly for office buildings in temperate or hot climates. When people talk about siting and building orientation, they tend to think about a building design independent from it's context, where a scheme is plunked down onto the site and rotated until it magically finds the right orientation.

By altering the orientation, the only thing that you're doing is changing the amount of solar gain entering your spaces at different times of day and in different seasons. If you instead focus specifically on solar gain at a schematic level you can derive optimal building forms and have a better idea of where to place the glass and the solid elements of your design - a strategy much more effective than the drop and rotate method. Now with the Solar Radiation Technology plug-in you can instantly do this analysis on building masses in Revit Architecture and in Revit MEP.

By default the roofs and floors are included in the solar insolation analysis, but it's fairly easy to select these faces and either exclude them or include them as shading elements. By ignoring the roof elements the color scale will adjust to give a better visual understanding of which vertical surfaces are more suited for glazing.To test interoperability I imported an object from Rhino and found that the analysis worked just as well on imported masses. It was actually much easier to import it from Rhino into Revit for the insolation analysis than it would be to take it directly from Rhino into Ecotect.

I do have one concern about this process: are the calculations made on the squares or on the corner points? With triangles it is easy to know the direction normal to the surface, but on out-of-plane squares it is impossible without further triangulation. Perhaps the values are determined for the corner points and averaged across the square, in which case contour lines would display more accurate results. In any case it would be interesting to learn the calculation methods being used.

My critique/wish list for the Solar Radiation Analysis plug-in:

I'd like to have the ability to extract the values for both the solar radiation and the area of the surface collecting the radiation. This would allow us to better compare options numerically, and to also determine the amount of energy that could be collected using PV systems.

I'd like the ability to include object surfaces (in addition to mass surfaces) as either shading or analysis surfaces. This functionality would allow me to optimize shading devices using the outer face of a window as the analysis surface. By default, all objects other than masses need to stay out of this process so that the calculation time stays small.

The ability to distinguish between direct and diffuse radiation. While they both contribute to Solar gain, I tend to want diffuse radiation much more than I want direct radiation simply because diffuse light is necessary for good daylighting.